JP6928688B2 - Confocal displacement meter - Google Patents

Description

The present invention relates to a confocal displacement meter, and more particularly to an improvement of a confocal displacement meter that measures a distance to a detection object by utilizing axial chromatic aberration by a confocal optical system.

The cofocal displacement meter has the cofocal principle of narrowing down the light received by the reflected light from the image plane on which the image of the light source for projection is formed, and the image of the light source for projection causes chromatic aberration in the optical axis direction. This is an optical distance measuring device that measures the distance to the work by utilizing the phenomenon of axial chromatic aberration (for example, Patent Documents 1 and 2). For example, a confocal displacement meter includes a light source for projection, a confocal optical system, a spectroscope, and a line sensor.

The light source for projection produces detection light composed of light having a plurality of wavelengths. The cofocal optical system has an objective lens that emits the detected light toward the work, and causes axial chromatic aberration in the image of the light source for projection by the detected light. The spectroscope disperses the reflected light that has passed through the confocal optical system after being reflected by the work. The line sensor is composed of a plurality of light receiving elements that receive the dispersed reflected light and generate a light receiving signal. Each light receiving element is linearly arranged.

Since the position of the image plane differs for each wavelength due to axial chromatic aberration, the reflected light received by the line sensor is narrowed down to the wavelength component imaged and reflected on the work. The distance to the work is measured by acquiring a light receiving waveform consisting of a light receiving intensity distribution with respect to the distance based on the light receiving signal and specifying the peak position. By this distance measurement, it is possible to detect the amount of movement of the work, the height of the work, and the like. Further, it is possible to detect the thickness of the transparent body and the like only by acquiring one light receiving waveform. According to such a confocal displacement meter, it is not easily affected by the material, color, and inclination of the workpiece when measuring the distance.

The conventional confocal displacement meter has a problem that the amount of light of the light source for projection is small and the measurable work is limited. For example, when a work with low surface reflectance or a work with a mirror-like surface is detected from an oblique direction, if the amount of light projected is small, sufficient light reception intensity cannot be obtained and the signal waveform is buried in noise. , It becomes difficult to identify the peak position.

Japanese Unexamined Patent Publication No. 2013-13580 Japanese Unexamined Patent Publication No. 2014-115242

As described above, the conventional confocal displacement meter has a small amount of light from the light source for projection. Therefore, it is conceivable to increase the output of the light source for floodlight to support various workpieces. However, if the output of the light source for projection is increased, the influence of the reflected light by the member other than the work cannot be ignored, and the peak position is shifted by the received light waveform corresponding to the reflected light, so that the measurement accuracy is lowered. There is a problem.

For example, as a method of removing the influence of reflected light from a member other than the work, a first method using a light receiving waveform acquired in the absence of a work and a second method using a rate of change in light receiving intensity are used. be. In the first method, the signal waveform is obtained from the difference between the light-receiving waveform acquired in the presence of the work and the light-receiving waveform obtained in the absence of the work, and the peak position is specified. In this first method, it is necessary to acquire two received light waveforms having different measurement timings. Therefore, the work efficiency is not good and it is difficult to use. In addition, when a change with time occurs in the light source for projection, the optical component of the confocal optical system, the light receiving element, etc. between the acquisition of the first light receiving waveform and the acquisition of the second light receiving waveform. , The signal waveform cannot be obtained correctly.

On the other hand, the second method utilizes the fact that the light-receiving waveform corresponding to the light reflected from the member other than the work gradually changes with respect to the light-receiving waveform corresponding to the light reflected from the work. This is a method of making it less susceptible to the influence of the reflected light from the member of the above, and the peak position is specified by comparing the rate of change of the light receiving intensity with the threshold value. Since this second method does not identify the received light waveform corresponding to the reflected light from the member other than the work, it is not possible to prevent the peak position from shifting due to the received light waveform.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a confocal displacement meter capable of improving measurement accuracy while being able to handle various detection objects. In particular, it is an object of the present invention to provide a confocal displacement meter capable of improving measurement accuracy without lowering work efficiency.

The cofocal displacement meter according to the first aspect of the present invention includes a light projecting light source that generates detection light composed of light having a plurality of wavelengths, and an objective lens that emits the detection light toward a detection object. A confocal optical system that causes axial chromatic aberration in the detected light, a spectroscope that disperses the reflected light that has been reflected by the detection object and then passed through the cofocal optical system, and the dispersed reflected light. Based on two or more light receiving elements that receive light and generate a light receiving signal, a light receiving waveform acquisition means that acquires a light receiving waveform consisting of a distribution of light receiving intensity with respect to the distance based on the light receiving signal, and a shape of the light receiving waveform. , The base waveform estimation means for estimating the base waveform, the signal waveform calculation means for obtaining the signal waveform based on the received light waveform and the base waveform, and the distance to the detection object based on the signal waveform. It is provided with a distance calculation means.

The cofocal displacement meter according to the second aspect of the present invention includes a light projecting light source that generates detection light composed of light having a plurality of wavelengths, and an objective lens that emits the detection light toward a detection object. The confocal optical system that causes axial chromatic aberration in the detected light, the spectroscope that disperses the reflected light that has been reflected by the detection object and then passed through the cofocal optical system, and the dispersed reflected light. Two or more light receiving elements that receive light and generate a light receiving signal, a light receiving waveform acquiring means that acquires a light receiving waveform consisting of a distribution of light receiving intensity with respect to the distance based on the light receiving signal, and the objective lens that did not emit light. A base waveform removing means for extracting a signal waveform from the received light waveform by removing the base waveform corresponding to the detected light, and a distance calculating means for obtaining the distance to the detection target based on the signal waveform. Be prepared.

According to such a configuration, the signal waveform is obtained from the received light waveform to obtain the distance to the detection target. Therefore, even when the output of the light source for projection is increased, the reflected light by a member other than the detection target is obtained. The influence of the above can be reduced and the measurement accuracy can be improved. Therefore, it is possible to improve the measurement accuracy while being able to deal with various detection objects. Further, since it is not necessary to acquire the received light waveform in the absence of the inspection object, the measurement accuracy can be improved without lowering the work efficiency.

In addition to the above configuration, the confocal displacement meter according to the third aspect of the present invention includes an exposure time adjusting means for adjusting the exposure time of the light receiving element based on the light receiving signal. According to such a configuration, the exposure time is set according to the object to be detected by the automatic adjustment of the exposure time, so that the distance can be measured with high accuracy.

In addition to the above configuration, the confocal displacement meter according to the fourth aspect of the present invention includes a waveform data output means for outputting waveform data for displaying the signal waveform on a screen to an external device. According to such a configuration, the signal waveform can be displayed on the screen in the external device.

In the confocal displacement meter according to the fifth aspect of the present invention, in addition to the above configuration, the base waveform estimation means sets a reference range at a fixed distance with respect to a data point sequence consisting of two or more data points constituting the received light waveform. A representative point sequence generation means for generating a representative point sequence consisting of two or more representative points by obtaining a regression curve that fits to the data point sequence within the reference range and determining a representative point each time the movement is performed. The intensity difference calculating means for obtaining the difference in light receiving intensity between the data points and the representative points, the weighting coefficient calculating means for obtaining the weighting coefficient based on the difference, and the weighting coefficient assigned to the data point sequence, refer to the above. A representative point sequence updating means for updating the representative point sequence by finding a regression curve that weights and fits the data point sequence in the reference range each time the range is moved by a certain distance and newly determining a representative point. The above-mentioned base waveform is composed of the updated representative point sequence.

The signal waveform has a shape having a sharp peak at a position corresponding to a specific wavelength. On the other hand, the basal waveform corresponding to the reflected light from the member other than the detection object contains various wavelength components and has a shape that gradually changes. Therefore, by suppressing the influence of data points whose light receiving intensity deviates significantly from the representative point sequence, the light receiving waveform corresponding to the detected light not emitted from the objective lens can be correctly estimated as the base waveform.

The confocal displacement meter according to the sixth aspect of the present invention is configured to include a reference range receiving means for receiving the reference range in addition to the above configuration. According to such a configuration, the basal waveform can be correctly estimated by adjusting the reference range according to the optical characteristics of the light source for projection and the confocal optical system.

According to the present invention, even when the output of the light source for projection is increased, the influence of the reflected light by the member other than the detection target is reduced, so that the measurement can be performed while being able to handle various detection targets. It is possible to provide a confocal displacement meter that can improve the accuracy. Further, since it is not necessary to acquire the received light waveform in the absence of the inspection object, it is possible to provide a confocal displacement meter capable of improving the measurement accuracy without lowering the work efficiency.

It is a system diagram which showed one structural example of the confocal displacement meter 1 by embodiment of this invention. It is sectional drawing which shows typically the structural example of the head unit 10 of FIG. It is a block diagram which showed the configuration example of the controller 20 of FIG. It is a figure which showed the structural example of the light source unit 21 for light projection of FIG. It is a block diagram which showed the structural example of the measurement control unit 27 of FIG. It is a block diagram which showed the structural example of the basal waveform estimation part 102 of FIG. FIG. 5 is a diagram showing an example of the operation of the measurement control unit 27 of FIG. 5, and shows a light receiving waveform 4, a basal waveform 5, and a signal waveform 6. It is a figure which showed an example of the operation at the time of basal waveform estimation by the measurement control unit 27 of FIG. 5, and shows how the representative point sequence is generated from the data point sequence which constitutes the received light waveform. Is a diagram illustrating an example of operation when base waveform estimated in the measurement control unit 27 of FIG. 5, are robust weight w _i, regression weights w _i and representative point sequence of the updated indicated. It is a flowchart which showed an example of the operation at the time of distance measurement in the measurement control unit 27 of FIG. It is sectional drawing which shows the other structural example of the light source unit 21 for light projection schematically. It is sectional drawing which showed the other structural example of the head unit 10. It is a figure which showed the other structural example of the controller 20, and shows the transmission type spectroscopic optical system. It is a figure which showed the other structural example of the confocal displacement meter 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present specification, for convenience, the direction of the optical axis of the detection light DL is described as the vertical direction, but the posture of the confocal displacement meter 1 and the head unit 10 according to the present invention is not limited.

<Confocal displacement meter 1>
FIG. 1 is a system diagram showing a configuration example of a confocal displacement meter 1 according to an embodiment of the present invention. The cofocal displacement meter 1 is composed of an optical fiber cable 2, a head unit 10 and a controller 20, and receives reflected light from the work W when the detection light DL is emitted from the head unit 10 and is a distance to the work W. It is an optical distance measuring device that measures.

The work W is a detection target. The head unit 10 and the controller 20 are connected via an optical fiber cable 2 that transmits a detection optical DL. A PC (personal computer) 3 is connected to the controller 20. The PC 3 sets measurement conditions and the like for the controller 20, acquires measurement results and the like from the controller 20, and displays them on the screen.

The head unit 10 is a light emitting / receiving unit that emits detection light DL composed of white light toward the work W and receives reflected light from the work W. The optical fiber cable 2 is a transmission medium for transmitting the detection optical DL, and is composed of a thin wire-shaped core extending in the long direction and a clad surrounding the core. The controller 20 is a control unit that controls light emission and reception and calculates the distance to the work W based on the reflected light from the work W.

Since the detection light DL and the reflected light are transmitted between the controller 20 and the head unit 10 via the optical fiber cable 2, the head unit 10 can be miniaturized. Further, the head unit 10 can be easily installed even at a place away from the controller 20.

<Head unit 10>
FIG. 2 is a cross-sectional view schematically showing a configuration example of the head unit 10 of FIG. 1, and shows a cut surface when the head unit 10 is cut by a vertical plane. The head unit 10 includes a cofocal optical system 11 composed of a fiber end 2a, a collimating lens 13 and an objective lens 14, and a housing 12 accommodating the cofocal optical system 11. The housing 12 is a lidded cylindrical lens barrel.

The fiber end 2a is an end portion of the optical fiber cable 2 on the head unit side, and functions as a pinhole of the confocal optical system 11. Specifically, the clad of the optical fiber cable 2 acts as a light-shielding member that blocks the return light to the optical fiber cable 2, and the end face of the core acts as an opening of a pinhole. A confocal effect can be obtained by blocking the return light. A light-shielding plate having a minute opening (through hole) as a pinhole may be arranged between the fiber end 2a and the collimating lens 13.

The fiber end 2a is arranged so as to project downward from the canopy portion of the housing 12. The collimating lens 13 is a condensing lens that condenses the detection light DL emitted from the fiber end 2a into parallel light. The collimating lens 13 faces the end surface of the fiber end 2a and is arranged so that the optical axis coincides with the fiber end 2a.

The objective lens 14 is a condensing lens that emits the detection light DL toward the work W. The objective lens 14 faces the collimating lens 13 and is arranged so that the optical axis coincides with the collimating lens 13. The collimating lens 13 and the objective lens 14 cause axial chromatic aberration in the detection light DL. Axial chromatic aberration is a color shift of an image in the optical axis direction due to dispersion.

The optical system in the head unit 10 is not limited to the configuration shown in FIG. 2, and may have a configuration as shown in FIG. Further, a configuration in which a diffractive lens is used instead of the collimating lens 13 or a configuration in which the diffractive lens is used as the objective lens 14 may be used. That is, in the optical system in the head unit 10, axial chromatic aberration is given in the head unit 10 to white light having a multi-wavelength component emitted from the fiber end 2a, and the axis is directed from the head unit 10 toward the work W. Any light may be emitted as long as it emits light having chromatic aberration.

The confocal optical system 11 narrows down the light to be received by using the confocal principle, and causes axial chromatic aberration in the detected light DL. The detection light DL emitted from the fiber end 2a and transmitted through the collimating lens 13 and the objective lens 14 is imaged at different positions in the vertical direction depending on the wavelength. Of the wavelength components contained in the detection light DL, a specific wavelength component imaged on the work W is reflected by the work W, and the reflected light passes through the objective lens 14 and the collimating lens 13 to pass through the objective lens 14 and the collimating lens 13 to the end face of the fiber end 2a. Image on top. On the other hand, the reflected light corresponding to a wavelength component other than the specific wavelength component is not imaged on the end face of the fiber end 2a and is blocked by the fiber end 2a.

For example, the diameter of the core of the fiber end 2a is preferably 200 μm or less, and more preferably 50 μm or less. The distance from the objective lens 14 to the work W is about 20 mm to 70 mm, and the measurement range MR is about ± 1 mm to ± 20 mm.

<Controller 20>
FIG. 3 is a block diagram showing a configuration example of the controller 20 of FIG. The controller 20 includes a light source unit 21 for floodlight, a splitter 22, a lens for a spectroscope 23, a spectroscope 24, an imaging lens 25, a line sensor 26, a measurement control unit 27, and a display unit 28. The fiber end 2b, the spectroscopic lens 23, the spectroscope 24, the imaging lens 25, and the line sensor 26 constitute a spectroscopic optical system.

The light source unit 21 for projection generates a detection light DL composed of white light containing two or more wavelength components. The splitter 22 transmits the detection light DL incident from the light source unit 21 for projection via the optical fiber cable 2 toward the head unit 10, while the splitter 22 transmits the detection light DL incident from the head unit 10 via the optical fiber cable 2. It is an optical member that transmits light toward a spectroscopic optical system.

The fiber end 2b is an end portion of the optical fiber cable 2 on the spectroscopic optical system side. The spectroscope lens 23 is a condensing lens that collects the light emitted from the fiber end 2b. The spectroscope lens 23 faces the end surface of the fiber end 2b and is arranged so that the optical axis coincides with the fiber end 2b.

The spectroscope 24 is an optical member that disperses the light reflected by the work W and passed through the confocal optical system 11. The spectroscope 24 is a reflection type spectroscope that disperses incident light into different wavelength components according to the reflection angle, and is composed of a flat plate-shaped diffraction grating. The imaging lens 25 is a condensing lens that forms an image of the dispersed reflected light on the line sensor 26.

The line sensor 26 is composed of two or more light receiving elements that are separated by the spectroscope 24, receive light transmitted through the imaging lens 25, and generate a light receiving signal. Each light receiving element is linearly arranged. For example, the line sensor 26 is composed of an image pickup device such as a multi-segment PD (photodiode), a CCD (charge-coupled device), or a CMOS (complementary metal oxide semiconductor). The multi-segment PD is a light receiving element unit in which a large number of PDs are two-dimensionally arranged on a circuit board.

The measurement control unit 27 calculates the distance to the work W based on the received signal from the line sensor 26, and displays the measurement result on the display unit 28. Further, the measurement control unit 27 acquires a light-receiving waveform and a signal waveform, which will be described later, based on the light-receiving signal, and outputs the waveform data to the PC3. The display unit 28 includes a 7-segment display provided in the housing of the controller 20, and displays a measured distance value, a determination threshold value, and the like.

<Light source unit for floodlight 21>
4A and 4B are views showing a configuration example of the light source unit 21 for light projection of FIG. 3. FIG. 4A shows a side surface of the light source unit 21 for light projection, and FIG. The cut surface when the light source unit 21 for floodlight is cut by the AA line is shown. The light source unit 21 for light projection is composed of a light emitting element 211, a wiring board 212, an element holder 213, a condenser lens 214, a lens holder 215, a ferrule 216, a ferrule holder 217, a phosphor 220, a frame body 221 and a reflective filter 222. It is composed.

The light emitting element 211 is a laser light source for exciting a phosphor that generates a laser beam having a single wavelength. The light emitting element 211 is arranged on the wiring board 212 with the light emitting portion facing forward in the horizontal direction. For example, the light emitting element 211 produces blue light or ultraviolet light having a wavelength of 450 nm or less. The element holder 213 is a member that holds the wiring board 212, and is inserted into the lens holder 215 from the back side.

The condensing lens 214 is an optical member that condenses the laser light emitted from the light emitting element 211 on the fiber end of the optical fiber cable 2 on the light source unit side for light projection, and is arranged so as to face the light emitting element 211. .. The lens holder 215 is a lens barrel that holds the condenser lens 214, and has a reduced diameter in front of the condenser lens 214. The ferrule 216 is a cylindrical connecting member in which the fiber end of the optical fiber cable 2 on the light source unit side for light projection is incorporated and extends in the front-rear direction. The ferrule presser 217 is a bottomed cylindrical member for fixing the ferrule 216 inserted from the front side to the reduced diameter portion of the lens holder 215, and the cylindrical portion is covered with the outer peripheral surface of the reduced diameter portion. It is attached to the lens holder 215.

The phosphor 220 is a light emitter that is excited by the laser light from the light emitting element 211 and generates fluorescence having a wavelength different from that of the laser light. The outer peripheral surface of the phosphor 220 is held by the frame body 221 and is arranged in the lens holder 215 in a state of being in contact with the end surface of the fiber end of the optical fiber cable 2. For example, the phosphor 220 emits yellow fluorescence by irradiation with a blue laser beam. The phosphor 220 may be formed of two or more types of fluorescent materials. For example, the phosphor 220 is formed of a fluorescent material that generates green fluorescence and a fluorescent material that generates red fluorescence when irradiated with a blue laser beam.

The reflection type filter 222 is an optical member that transmits the laser light from the light emitting element 211 and reflects the light from the phosphor 220, and is arranged so as to cover the surface of the frame 221 on the light emitting element side. At the fiber end of the optical fiber cable 2, light having a plurality of wavelengths in which the laser light from the light emitting element 211 and the fluorescence from the phosphor 220 are mixed is incident as the detection light DL.

The light source unit 21 for floodlight has a configuration in which light obtained by mixing laser light from the light emitting element 211 and fluorescence from the phosphor 220 is directly incident on the fiber end of the optical fiber cable 2. By using such a fiber type light source, it is possible to simplify the connection between the head unit 10 and the controller 20 with the optical fiber cable 2.

<Measurement control unit 27>
FIG. 5 is a block diagram showing a configuration example of the measurement control unit 27 of FIG. The measurement control unit 27 includes a light receiving waveform acquisition unit 101, a base waveform estimation unit 102, a signal waveform calculation unit 103, a distance calculation unit 104, a conversion type storage unit 105, a waveform data output unit 106, a reference range reception unit 107, and an exposure time. It is composed of an adjusting unit 108 and a light projecting amount control unit 109.

The light-receiving waveform acquisition unit 101 acquires a light-receiving waveform consisting of a distribution of light-receiving intensity with respect to distance based on the light-receiving signal from the line sensor 26, and outputs the light-receiving waveform to the basal waveform estimation unit 102 and the signal waveform calculation unit 103. Since a large number of light receiving elements are linearly arranged in the line sensor 26, light receiving intensity data indicating the amount of light received by each light receiving element is managed in association with the position in the arrangement direction. If the position in the arrangement direction of the light receiving elements is called a pixel position, the light receiving waveform is composed of a large number of light receiving intensity data associated with each pixel position.

The basal waveform estimation unit 102 estimates the basal waveform based on the shape of the light receiving waveform acquired by the light receiving waveform acquisition unit 101. The base waveform is a light receiving waveform showing a noise component, and corresponds to the detection light DL not emitted from the objective lens 14 of the head unit 10. The signal waveform calculation unit 103 obtains a signal waveform based on the received light waveform and the base waveform, and outputs the signal waveform to the distance calculation unit 104 and the waveform data output unit 106. The signal waveform is a light receiving waveform corresponding to the detection light DL emitted from the objective lens 14 and reflected by the work W, and is obtained from the difference between the light receiving waveform and the base waveform. The base waveform estimation unit 102 and the signal waveform calculation unit 103 are base waveform removing means for extracting a signal waveform from a received waveform by removing the base waveform corresponding to the detection light DL not emitted from the objective lens 14.

The distance calculation unit 104 obtains the distance WD to the work W based on the signal waveform obtained by the signal waveform calculation unit 103, and outputs the distance WD to the display unit 28. Since the pixel position on the received light waveform corresponds to the wavelength of the light imaged at the corresponding position on the line sensor 26 and the wavelength corresponds to the distance WD, the distance WD specifies the peak position of the signal waveform. Demanded by.

For example, if there is a data point sequence whose light receiving intensity is equal to or higher than the determination threshold value for the data point sequence constituting the signal waveform, it is determined that the data point sequence corresponds to the reflected light component from the work W, and the light receiving intensity is maximum in the data point sequence. The pixel position of the data point of is specified as the peak position. Alternatively, a curve that fits into a data point sequence whose light receiving intensity is equal to or greater than the determination threshold value may be obtained, and the pixel position of the maximum point of the curve may be set as the peak position.

Further, the distance calculation unit 104 obtains the displacement amount by comparing the calculated distance WD with the reference value, and outputs the displacement amount to the display unit 28. The conversion formula storage unit 105 holds a conversion formula or a table for associating the pixel position, wavelength, and distance WD with each other.

The waveform data output unit 106 outputs waveform data for displaying the signal waveform obtained by the signal waveform calculation unit 103 on the screen to the PC3. The reference range reception unit 107 receives the reference range RR, which will be described later, from the PC3. The reference range RR is a processing unit for analyzing the data point sequence constituting the received light waveform, and the basal waveform is estimated based on the reference range RR.

In the confocal displacement meter 1 according to the present embodiment, the amount of light received is controlled so that the light receiving intensity is not saturated even if the reflectance changes depending on the type of the work W and the portion inside the work W. .. For example, if the work W is an object that specularly reflects, the maximum value of the light receiving intensity is high, while if the work W is an object such as a transparent body, the maximum value of the light receiving intensity is low. Regardless of the type of the work W, in order to perform stable displacement measurement, it is necessary to change the amount of light received by the light receiving device (line sensor 26) so that the maximum value of the light receiving intensity is not saturated. The method of changing the amount of light received by the light receiving device (line sensor 26) is a method of adjusting the gain of the amplifier that amplifies the light receiving signal and a method of changing the exposure amount of the light receiving device by adjusting the exposure time of the light receiving device. There is a method of adjusting the amount of light projected by the light projecting device. The exposure time adjusting unit 108 and the light projecting amount control unit 109 are means for changing the dynamic range of such light receiving intensity.

For example, when the maximum value of the light receiving intensity is saturated, the time for opening the shutter of the light receiving device is shortened in order to reduce the amount of light received by the light receiving device so that the maximum value of the light receiving intensity is not saturated at the next sampling. do.

The exposure time adjusting unit 108 adjusts the exposure time of the light receiving element in the line sensor 26 based on the light receiving signal from the line sensor 26. For example, the exposure time is determined by controlling the time of charge accumulation in the light receiving element. Further, the exposure time is shortened when the light receiving intensity exceeds a certain level.

The light projection amount control unit 109 controls the light projection amount of the detection light DL based on the received light signal from the line sensor 26. For example, the amount of light projected from the detection light DL is adjusted by controlling the light emitting element 211 that generates the laser light and changing the pulse time (pulse width) of the laser light. By adjusting the exposure time or controlling the amount of light projected as described above, the light receiving intensity fluctuates with time, so that the base waveform changes. Since the basis waveform estimation unit 102 estimates the basis waveform from the current received light waveform, the dynamically changing basis waveform is automatically obtained. By subtracting the base waveform obtained in this way from the received light waveform, the correct signal waveform can be obtained even if the dynamic range changes depending on the surrounding environment or the work W. The dynamic range of the light receiving intensity may be changed by adjusting the gain of the amplifier that amplifies the light receiving signal.

<Basis waveform estimation unit 102>
FIG. 6 is a block diagram showing a configuration example of the basal waveform estimation unit 102 of FIG. The basal waveform estimation unit 102 is composed of a representative point sequence generation unit 111, a representative point sequence storage unit 112, an intensity difference calculation unit 113, a weight coefficient calculation unit 114, and a representative point sequence update unit 115.

The representative point sequence generation unit 111 generates a representative point sequence composed of two or more representative point RPs based on the light receiving waveform from the light receiving waveform acquisition unit 101, and stores the representative point sequence in the representative point sequence storage unit 112. The received light waveform is composed of a data point sequence composed of two or more data point DPs. Each data point DP is associated with the light receiving intensity data of the corresponding light receiving element and the position information indicating the pixel position.

The representative point RP obtains a regression curve RC that fits the data point sequence in the reference range RR including the attention point AP, and obtains the light receiving intensity data corresponding to the pixel position of the attention point AP. It is determined by calculating from. The point of interest AP is any data point DP within the reference range RR. The regression curve RC is obtained using the method of least squares. The representative point sequence is obtained by determining the representative point RP by obtaining the regression curve RC fitting to the data point sequence in the reference range RR every time the reference range RR is moved by a certain distance Δx.

The intensity difference calculation unit 113 obtains the residual d between the data point DP and the representative point RP, and outputs the residual d to the weight coefficient calculation unit 114. The residual d is the difference in light receiving intensity between the data point DP and the representative point RP.

The weight coefficient calculation unit 114 obtains the weight coefficient w based on the residual d from the strength difference calculation unit 113, and outputs the weight coefficient w to the representative point sequence update unit 115. The weighting coefficient w is a real number of 0 or more and 1 or less, and is determined so that it becomes larger as the residual d is smaller and becomes 0 in the range where the residual d exceeds a certain value.

The representative point sequence update unit 115 assigns a weighting coefficient w to the data point sequence, and obtains a regression curve RC that weights and fits the data point sequence in the reference range RR each time the reference range RR is moved by a certain distance Δx. By newly defining the representative point RP, the representative point sequence will be updated. The process of obtaining the weighting coefficient w according to the residual d and updating the representative point sequence is repeated a certain number of times. The basis waveform is composed of the updated representative point sequence.

7A and 7B are views showing an example of the operation of the measurement control unit 27 of FIG. 5, in which the light receiving waveform 4 is shown in FIG. 7A and the basal waveform 5 is shown in FIG. , (C) show the signal waveform 6. In the figure, the light receiving waveform 4, the basal waveform 5, and the signal waveform 6 are drawn with the horizontal axis as the pixel position and the vertical axis as the light receiving intensity. Further, in (c) in the figure, the signal waveform 6 exaggerated displacement of the peak position P ₃ with respect to the light receiving waveform 4 is drawn.

The light receiving waveform 4 is a characteristic curve representing the relationship between the pixel position and the light receiving intensity, and is created based on the light receiving signal. In the received light waveform 4, sharp peaks are formed on the short wavelength side and the long wavelength side, and one peak in which the light receiving intensity gradually changes is formed between these peaks. The peak waveform on the short wavelength side is a received light waveform corresponding to the laser beam for exciting the phosphor. The peak waveform on the long wavelength side corresponds to the signal waveform 6. The peak waveform on the short wavelength side and the gradually changing peak waveform correspond to the base waveform 5. By using light having a strong amount of light, for example, light using a laser as a light source, the intensity of the base waveform 5 is also increased.

Base waveform 5, pixel location analyzes p ₁ or p ₂ less the scope as a calculation target range shape of the light-receiving waveform 4 in the calculation target range, smoothly fitting the data point sequence constituting the light receiving waveform 4 Obtained by estimating the curve as the baseline.

Pixel position p _1, in order to eliminate the influence of the peak waveform of the short wavelength side is predetermined to the long wavelength side than the peak waveform. The signal waveform 6 is a received light waveform corresponding to the reflected light from the work W, and is obtained by subtracting the base waveform 5 from the received light waveform 4.

By using a laser light source as the light source for projection and using the mixed light of the laser light and the fluorescence from the phosphor 220 excited by the laser light as the detection light DL, the amount of light of the detection light DL is extremely large. Therefore, the influence of the reflected light by the members other than the work W cannot be ignored. The light receiving waveforms corresponding to the reflected light by members other than work W is ground wave 5, the light receiving waveform 4, the presence of base waveform 5, there is a problem that the peak position P ₃ of the signal waveform 6 is shifted.

For example, the base waveform 5 is chevron-shaped, if the signal waveform 6 is formed on the inclined region of the longer wavelength side than the peak position, the peak position P ₃ of the signal waveform 6, the peak position side of the base waveform 5, That is, it shifts to the short wavelength side. This is because the rate of change in the vicinity of the apex of the signal waveform 6 is about 0, whereas the rate of change in the inclined region of the base waveform 5 is larger than 0.

In the present embodiment, for obtaining a signal waveform 6 by estimating the base waveform 5 from the shape of the light receiving waveform 4, without being affected by the base waveform 5, to detect the peak position P ₃ of the signal waveform 6 accurately Can be done. Since the confocal displacement meter 1 calculates this base waveform 5 based on the shape of the waveform, the user is made to remember the correction value every time the work W, the measurement environment, or the measurement condition is changed. It takes less time and effort than the correction. Further, even when the dynamic range changes, the basal waveform 5 also changes according to the fluctuation of the dynamic range, and the peak position of the signal waveform 6 can be correctly specified.

FIG. 8 is a diagram showing an example of an operation at the time of estimating the basal waveform in the measurement control unit 27 of FIG. 5, and shows how a representative point sequence is generated from the data point sequence constituting the received light waveform 4. In (a) in the figure, a data point sequence composed of a large number of data point DPs constituting the received light waveform 4 is shown. The dots indicating the data point DP are plotted with the horizontal axis representing the position x on the line sensor 26 and the vertical axis representing the light receiving intensity y. The distance between each data point DP in the x-axis direction is constant.

In (b) in the figure, a state in which the representative point RP is determined by obtaining the regression curve RC fitting to the data point sequence in the reference range RR is shown. The reference range RR is a processing target area for statistical calculation by the least squares method, and is composed of two or more consecutive data point DPs including a point of interest AP. In this example, the point of interest AP is the center data point DP, and the reference range is a region containing three data point DPs at a position larger than the point of interest AP and three data point DPs at a position smaller than the point of interest AP. It is designated as RR. That is, the reference range RR includes seven data point DPs.

The regression curve RC is represented by a function of Nth order (N is an integer of 1 or more) to be fitted to the data point sequence in the reference range RR. The regression curve RC is obtained by defining an Nth-order function that approximates the data point sequences in the reference range RR by using the least squares method.

The representative point RP is determined based on the point of interest AP and the regression curve RC. That is, the representative point RP is determined by calculating the y-coordinate (light receiving intensity) corresponding to the x-coordinate of the point of interest AP from the regression curve RC. In this example, cross marks indicating the representative point RP are plotted within the reference range RR.

For example, the data points in the reference range RP n, the coordinates of each data point _{DP (x i, y i)} (i is an integer from 1 to n), and two regression curve RC linear function y = ax ² If + bx + c, the parameters a, b, and c can be obtained by the following equation (1).

In (c) in the figure, a representative point sequence consisting of two or more representative point RPs acquired based on the data point sequence within the calculation target range is shown in comparison with the data point sequence. The statistical calculation process of obtaining the regression curve RC fitting to the data point sequence in the reference range RR and determining the representative point RP is repeated every time the reference range RR is moved by Δx in the x-axis direction.

The movement amount Δx is arbitrary as long as it has a value equal to or greater than the pitch of the data point sequence in the x-axis direction. In this example, the movement amount Δx coincides with the pitch of the data point sequence. By defining the representative point RP for all the data point DPs in the calculation target range, the basis waveform 5 of the 0th order approximation is acquired. In this basal waveform 5, the waveform is locally uneven in a form of being pulled by the data point DP corresponding to the signal component.

For example, the width of the reference range RR, the movement amount Δx, and the order N of the regression curve RC are parameters indicating measurement conditions, and can be arbitrarily specified by the user according to the curvature of the base waveform 5 and the signal waveform 6. .. Such parameters can be set for each head unit 10, and the set values are held in the controller 20. The order N may be a fixed value.

Figure 9 is a diagram illustrating an example of operation when base waveform estimated in the measurement control unit 27 of FIG. 5, how to update the representative point sequence using the weighting coefficients w _i that corresponds to the residual d _i is shown Has been done. The (a) in the figure, the horizontal axis represents the residual d _i, the vertical axis represents the weight coefficient w _i, is robust weight is shown for use in statistical calculation for updating the representative point sequence.

Residual d _i, if the representative point sequence are calculated at the same interval as data point sequences is determined by the difference in y-coordinate between the representative points RP and the corresponding data points DP. When the interval of the representative point sequence is wider than that of the data point sequence, the representative point RP corresponding to the data point DP is obtained by the interpolation process. Straight line interpolation and curve interpolation are used for the process of interpolating between the representative point RPs.

Robust weights are determined according to a method of robust estimation in which weights assigned to outliers that deviate significantly from other measured values are relatively small in order to suppress the influence of defective parts. For example, the weight coefficient w _i of the robust weights a coefficient for adjusting the degree of change of the weight is C, if the standard deviation of the residuals d _i and sigma, represented by the formula (2).

The weight coefficient w _i is represented by the characteristic curve of the normal distribution type, the maximum (maximum 1.0) at the position of the residual d _i is 0, decreases as the absolute value of the residual d _i increases , it is 0 in absolute value C × sigma or more positions of the residual d _i. For example, the coefficient C is about 3.0. Instead of the standard deviation sigma, it may determine the weighting coefficients w _i by using a central value m for all of the residual d _i. In the case of using a median value m in the weight coefficient _{w i,} the coefficient C is about 6.0.

In (b) in the figure, the horizontal axis difference value and (x i _{-x 0),} the vertical axis represents the weight coefficient w _i, with regression weights for use in statistical calculation for updating the representative point sequence is shown There is. The difference value (x _i − x ₀ ) is the difference between the x coordinate x _i of the data point DP and the x coordinate x ₀ of the point of interest AP.

The regression weight is determined by reducing the weight assigned to the data point DP distant from the attention point AP according to the distance in order to suppress the influence of the data point DP distant from the attention point AP centering on the attention point AP. Be done. For example, the weight coefficient w _i of the regression weights, if a coefficient for adjusting the degree of change in weight as L, is represented by the following equation (3).

This weighting coefficient w _{i is} also represented by a characteristic curve of a normal distribution type, and is the maximum (maximum value 1.0) at the position where _{the difference value (x i} − x _{0 ) is 0, and the difference value (x i} − x _0). ) Decreases as the absolute value increases, and the absolute value of the difference value (x _i − x ₀ ) is 0 at the position of L.

The base waveform 5 of first-order approximation, on the basis of the representative point sequence constituting the base waveform 5 of the zero-order approximation, determine the weight coefficient w _i, assign a weight coefficient w _i to the data point sequence, in the reference range RR It is obtained by finding the regression curve RC that fits the data point sequence with weights and newly defining the representative point RP. For example, if the regression curve RC is a quadratic function y = ax ² + bx + c, the parameters a, b, and c can be obtained by the following equation (4).

In (c) in the figure, the updated representative score sequence is shown in comparison with the data score sequence. The statistical calculation process of finding the regression curve RC that fits the data point sequence in the reference range RR with weight and newly determining the representative point RP is repeated every time the reference range RR is moved by Δx in the x-axis direction.

As the weighting coefficient wi of the above equation (4), the product of the robust weight shown in the above equation (2) and the regression weight shown in the above equation (3) is used. By newly defining the representative point RP for all the data point DPs in the calculation target range, the basis waveform 5 of the first-order approximation is acquired. In this base waveform 5, a waveform that changes smoothly without being affected by the data point DP corresponding to the signal component is obtained. By repeating M times the statistical processing of such a seeking residual d _i or difference value (x i _{-x 0)} weight coefficient w _i corresponding to update the representative point sequence, base waveform of M-th order approximation 5 can be obtained.

Steps S101 to S110 of FIG. 10 are flowcharts showing an example of an operation at the time of distance measurement in the measurement control unit 27 of FIG. First, the measurement control unit 27 acquires the received light waveform 4 based on the received signal and generates a representative point sequence (steps S101 and S102). Next, the measurement control unit 27, to the data point sequence in the reference range RR, calculates the weight coefficient _{w i} from the difference of the data points DP and the representative points RP seeking residual _{d i} (step S103, S104) ..

Next, the measurement control unit 27 assigns a weighting coefficient w to the data point sequence, obtains a regression curve RC that fits the data point sequence in the reference range RR with weight, and calculates a new representative point RP (step S105). , S106).

The processing procedure from step S103 to step S106 is repeated every time the reference range RR is moved by Δx until the update is completed for all the representative point RPs (steps S107 and S110). Further, the processing procedure from step S103 to step S107 is repeated a predetermined number of times (step S108).

The measurement control unit 27 repeats the processing procedure from step S103 to step S107 a specified number of times, and then calculates the signal waveform 6 from the difference in the y-coordinate between the data point sequence and the representative point sequence (step S109). The measurement control unit 27 calculates the distance WD to the work W and the amount of displacement by specifying the peak position of the signal waveform 6.

According to the present embodiment, since the signal waveform 6 is obtained from the received light waveform 4 to obtain the distance WD to the work W, even when the light source for projection is increased in output, reflection by a member other than the work W is obtained. The influence of light can be reduced and the measurement accuracy can be improved. In particular, by suppressing the influence of the data point DP whose light receiving intensity deviates significantly from the representative point sequence, the light receiving waveform corresponding to the detected light DL not emitted from the objective lens 14 can be correctly estimated as the base waveform 5. .. Further, since it is not necessary to acquire the received light waveform in the absence of the work W, the measurement accuracy can be improved without lowering the work efficiency.

Further, since the saturation of the light receiving element is suppressed by the automatic adjustment of the exposure time, the distance can be measured with high accuracy even for the work W having a high reflectance. Further, the basal waveform 5 can be correctly estimated by adjusting the width of the reference range RR, the movement amount Δx, and the interval of the representative point sequence according to the optical characteristics of the light source for projection and the confocal optical system 11. ..

Further, by calculating various feature quantities from the signal waveform 6 and comparing them with the reference values, it is possible to determine whether the work W is a normal work or a defective work. For example, a sequence of data points whose light receiving intensity is equal to or higher than the determination threshold value and which is continuous is regarded as one block, and the width, area, and position of the center of gravity in the x-axis direction are calculated as feature quantities for each block. Alternatively, for the data point sequence constituting the signal waveform 6, the maximum value, the minimum value, the average value, and the standard deviation of the light receiving intensity are obtained, and the total number of data points whose light receiving intensity is equal to or higher than the determination threshold value is obtained, and these statistical values are obtained. The work may be determined by comparing a characteristic amount with a reference value.

In the present embodiment, an example in which the light emitting element 211 and the fiber end of the optical fiber cable 2 are arranged coaxially has been described, but the present invention limits the configuration of the light source unit 21 for projection to this. It's not something to do. For example, the light source unit 21 for light projection includes a reflector that reflects the laser light emitted from the light emitting element 211 toward the fiber end of the optical fiber cable 2.

FIG. 11 is a cross-sectional view schematically showing another configuration example of the light source unit 21 for floodlight. The light source unit 21 for floodlight is composed of a light emitting element 211, a condenser lens 214, a ferrule 216, a phosphor 220, a reflector 231 and a condenser lens 232.

The laser light emitted from the light emitting element 211 is focused on the reflecting mirror 231 via the condenser lens 214. The phosphor 220 is arranged on the reflecting surface of the reflecting mirror 231 and is excited by the laser beam from the light emitting element 211 to generate fluorescence. The light obtained by mixing the laser light reflected by the reflector 231 and the fluorescence from the phosphor 220 is collected at the fiber end of the optical fiber cable 2 in the ferrule 216 via the condenser lens 232, and is collected by the optical fiber cable. 2 is incident as detection light DL.

Further, in the present embodiment, an example in which the cofocal optical system 11 of the head unit 10 is composed of the fiber end 2a, the collimating lens 13 and the objective lens 14 has been described, but the present invention describes the cofocal optical system. The configuration of 11 is not limited to this.

FIG. 12 is a cross-sectional view showing another configuration example of the head unit 10. In (a) in the figure, a head unit 10 having a diffractive lens 15 and an objective lens 14 inside the housing 12 is shown.

The diffractive lens 15 is a relief type diffractive lens, is an optical member that collects or diffuses incident light by utilizing the diffraction phenomenon of light, and has fine relief (undulations) on the incident surface or exit surface of the detection light DL. ) Is formed. The relief has a depth in the optical axis direction of about the wavelength of light, and a plurality of annular patterns centered on the optical axis are arranged coaxially.

In (b) in the figure, a head unit 10 including a doublet lens 16 and an objective lens 14 is shown. The doublet lens 16 is an optical member that combines a concave lens and a convex lens.

In (c) in the figure, a head unit 10 including a condenser lens 17 and an objective lens 14 is shown. The condensing lens 17 is an optical member that condenses the detection light DL emitted from the fiber end 2a toward the objective lens 14. In this head unit 10, a doublet lens is used as an objective lens 14.

In (d) in the figure, a head unit 10 including a condenser lens 17 and an objective lens 14 is shown. In this head unit 10, a diffractive lens is used as an objective lens 14. Even with such a combination of optical members, axial chromatic aberration can be caused in the detected light DL as the cofocal optical system 11. For example, a prism or a cylindrical lens having a refractive index distribution in the radial direction can be used as the cofocal optical system 11.

Further, in the present embodiment, an example in which the spectroscopic optical system is a reflection type has been described, but the present invention does not limit the configuration of the spectroscopic optical system to this. For example, a transmission type spectroscope that disperses incident light into different wavelength components depending on the transmission angle may be used as the spectroscope 24.

FIG. 13 is a diagram showing another configuration example of the controller 20, and shows a transmission type spectroscopic optical system. This spectroscopic optical system is composed of a fiber end 2b, a spectroscopic lens 23, a spectroscope 24, an imaging lens 25, and a line sensor 26.

The spectroscope 24 is a transmission type spectroscope that disperses the light emitted from the fiber end 2b of the optical fiber cable 2 and incident through the spectroscope lens 23, and is composed of a flat plate-shaped diffraction grating. The spectroscope 24 disperses incident light into different wavelength components depending on the transmission angle. The imaging lens 25 forms an image of the dispersed transmitted light on the line sensor 26.

Further, in the present embodiment, an example of the confocal displacement meter 1 in which the head unit 10 and the controller 20 are connected via the optical fiber cable 2 has been described, but the present invention describes the configuration of the confocal displacement meter 1. It is not limited to. For example, the confocal displacement meter 1 guides the detection light emitted from the light projecting light source to the confocal optical system without using an optical fiber cable, is reflected by the work, and passes through the confocal optical system. The configuration may be such that the light is directly guided to the spectroscopic optical system.

FIG. 14 is a diagram showing another configuration example of the confocal displacement meter 1. This confocal displacement meter 1 is not provided with an optical fiber cable, and has a light projecting light source 31, a condenser lens 32, 34, a pinhole plate 33, 37, an objective lens 35, a beam splitter 36, a spectroscope lens 23, and a spectroscope. 24, an imaging lens 25 and a line sensor 26.

The light source for projection 31 generates the detection light DL. The condenser lens 32 is an optical member that concentrates the detection light DL emitted from the light projection light source 31 on the opening of the pinhole plate 33, and is arranged so as to face the light emitting surface of the light projection light source 31. There is. The pinhole plate 33 is a flat plate-shaped light-shielding member having a minute opening.

The condenser lens 34 collects the detection light DL emitted from the opening of the pinhole plate 33 toward the objective lens 35. The objective lens 35 emits the detection light DL toward the work W. The condenser lenses 32 and 34, the pinhole plate 33, and the objective lens 35 are arranged coaxially.

The beam splitter 36 is an optical member that transmits the light from the pinhole plate 33, while is reflected by the work W and reflects the light transmitted through the objective lens 35 and the condenser lens 34 toward the pinhole plate 37. The pinhole plates 33 and 37, the condenser lens 34, the objective lens 35, and the beam splitter 36 are cofocal optical systems.

The spectroscope lens 23 collects the light emitted from the opening of the pinhole plate 37 toward the spectroscope 24. The spectroscope 24 is a reflection type spectroscope that disperses the light reflected by the work W and passed through the confocal optical system 11, and disperses the incident light into different wavelength components according to the reflection angle.

Further, in the present embodiment, an example in which the regression curve fitting to the data point sequence in the reference range is estimated by using the least squares method has been described, but the present invention describes the method of estimating the regression curve. It is not limited to. For example, the configuration may be such that the representative point sequence is determined by the moving averaging process for the data point sequence.

Further, in the present embodiment, an example in which a laser light source that generates laser light is used as a light source for projection has been described. An LED (light emitting diode) may be used as the light source for projection. Further, as the laser light source, an SC light source that generates SC (supercontinuum) light may be used. The SC light source generates continuous and wide band laser light by the nonlinear optical effect of the pulse laser.

Further, the light source unit 21 for light projection may be configured to include a light source that emits light in a wide wavelength band instead of the light emitting element 211 and the phosphor 220 that generate laser light. For example, the light source unit 21 for floodlight may include an LED (light emitting diode) or a halogen lamp that emits white light. The light source unit 21 for projection emits light having a wavelength of 500 nm to 700 nm, but may be configured to emit light in another wavelength band. For example, the light source unit 21 for floodlight may be configured to emit light in the infrared region or emit light in the ultraviolet region.

Further, in the present embodiment, the waveform can be displayed on the display unit of the PC3, but the waveforms to be displayed may be the waveforms of FIGS. 7A to 7C, respectively. By displaying the waveform excluding the basal waveform as shown in FIG. 7 (c) without displaying the waveform including the basal waveform as shown in FIG. 7 (a), the user can obtain the waveform corresponding to the desired displacement. Can be easily confirmed.

1 Confocal displacement meter 10 Head unit 11 Confocal optical system 12 Housing 13 Collimating lens 14 Objective lens 15 Diffractive lens 16 Doublet 20 Controller 21 Floodlight light source unit 22 Splitter 23 Spectral lens 24 Spectrometer 25 Imaging lens 26 line Sensor 27 Measurement control unit 28 Display unit 31 Floodlight light source 32, 34 Condensing lens 33, 37 Pinhole plate 35 Objective lens 36 Beam splitter 101 Light receiving waveform acquisition unit 102 Base waveform estimation unit 103 Signal waveform calculation unit 104 Distance calculation unit 105 Conversion type storage unit 106 Waveform data output unit 107 Reference range reception unit 108 Exposure time adjustment unit 109 Light emission control unit 2 Optical fiber cable 3 PC
4 Received waveform 5 Base waveform 6 Signal waveform

Claims (6)

With a laser light source
A condensing lens that collects the laser light from the above laser light source,
A phosphor that is excited by the laser beam from the condenser lens and generates a detection light having fluorescence whose light intensity with respect to a wavelength gradually changes.
A confocal optical system having an objective lens that emits the detected light toward the object to be detected and causing axial chromatic aberration in the detected light.
A spectroscope that disperses the reflected light of the detected light including the reflected light that has passed through the cofocal optical system after being reflected by the detection object, and a spectroscope.
An image sensor that receives the reflected light of the spectroscopic detection light and generates a light receiving signal.
Based on the received signal, the detection target has a peak shape in which the received intensity with respect to the wavelength changes sharply with respect to the mountain-shaped base waveform in which the received intensity with respect to the wavelength gradually changes in response to the reflected light of the detected light. A light receiving waveform acquisition means for acquiring a light receiving waveform including a signal waveform corresponding to the reflected light of
A light receiving light amount adjusting means for adjusting the received light amount of the reflected light of the detection light received by the image sensor, and a light receiving light amount adjusting means.
A basal waveform estimation means for estimating the basal waveform based on the shape of the received light waveform, and
A signal waveform calculation means for obtaining a signal waveform that corrects the influence of the base waveform by adjusting the received light amount by the received light amount adjusting means based on the received light waveform and the base waveform.
A confocal displacement meter provided with a calculation means for obtaining the displacement of the detection object based on the corrected signal waveform. With a laser light source
A condensing lens that collects the laser light from the above laser light source,
A phosphor that is excited by the laser beam from the condenser lens and generates a detection light having fluorescence whose light intensity with respect to a wavelength gradually changes.
A confocal optical system having an objective lens that emits the detected light toward the object to be detected and causing axial chromatic aberration in the detected light.
A spectroscope that disperses the reflected light of the detected light including the reflected light that has passed through the cofocal optical system after being reflected by the detection object, and a spectroscope.
An image sensor that receives the reflected light of the spectroscopic detection light and generates a light receiving signal.
Based on the received signal, the detection target has a peak shape in which the received intensity with respect to the wavelength changes sharply with respect to the mountain-shaped base waveform in which the received intensity with respect to the wavelength gradually changes in response to the reflected light of the detected light. A light receiving waveform acquisition means for acquiring a light receiving waveform including a signal waveform corresponding to the reflected light of
A light receiving light amount adjusting means for adjusting the received light amount of the reflected light of the detection light received by the image sensor, and a light receiving light amount adjusting means.
A basal waveform removing means that corrects the signal waveform of the received light waveform by removing the basal waveform that changes by adjusting the received light amount by the received light amount adjusting means.
A confocal displacement meter provided with a calculation means for obtaining the displacement of the detection object based on the corrected signal waveform. The confocal displacement meter according to claim 1 or 2, wherein the received light amount adjusting means includes an exposure time adjusting means for adjusting the exposure time of the image sensor based on the received signal. The confocal displacement meter according to any one of claims 1 to 3, further comprising a waveform data output means for outputting waveform data indicating the corrected signal waveform to an external device. The base waveform estimation means is a regression curve that fits to a data point sequence within the reference range each time the reference range is moved by a certain distance with respect to a data point sequence consisting of two or more data points constituting the received light waveform. A representative point sequence generation means for generating a representative point sequence consisting of two or more of the above representative points by determining the representative points.
Intensity difference calculating means for obtaining the difference in light receiving intensity between the data points and the representative points, and
A weighting coefficient calculating means for obtaining a weighting coefficient based on the above difference,
By assigning the weighting coefficient to the data point sequence and moving the reference range by a certain distance, a regression curve that fits the data point sequence within the reference range with weight is obtained and a representative point is newly determined. The symfocal displacement meter according to claim 1, further comprising a representative point sequence updating means for updating the representative point sequence, wherein the base curve is composed of the updated representative point sequence. The confocal displacement meter according to claim 5, further comprising a reference range receiving means for receiving the reference range.

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